<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .box{
            margin: 100px auto;
            width: 360px;
            padding-top: 360px;
            border: 1px solid gray;
            background: url(./image/01big.jpg) no-repeat;
        }
        .box>ul{
            list-style: none;
            height: 70px;
            border-top: 1px solid gray;
        }
        .box>ul>li{
            float: left;
            cursor: pointer;
        }
    </style>
    <script>
        window.onload=function(){
            var imgs = document.querySelectorAll('img');
            var box = document.querySelector('.box')
            for(let i=0;i<imgs.length;i++){
                imgs[i].onmouseover=function(){
                    box.style.backgroundImage='url(./image/0'+(i+1)+'big.jpg)'
                }
            }
        }
    </script>
</head>
<body>
    <div class="box">
        <ul>
            <li><img src="./image/01.jpg" alt=""></li>
            <li><img src="./image/02.jpg" alt=""></li>
            <li><img src="./image/03.jpg" alt=""></li>
            <li><img src="./image/04.jpg" alt=""></li>
            <li><img src="./image/05.jpg" alt=""></li>
        </ul>
    </div>
</body>
</html>